As far as we know, Vodafone Brussels doesn't support any internet-to-SMS gateways (like email to text, SNPP or WCTP) and their phones should be messaged by cellular hardware. It is possible, though, that Vodafone Brussels has a gateway that we're unaware of but you would need to contact the carrier to ask them what their email to SMS gateway is.

I would recommend using cellular hardware to message those recipients.